/* 	Class:
		HistoryManager

	Author:
		Neil Jenkins
		
	Version:
		1.2 (2007-09-21)
*/		
var HistoryManager = (function() {

	var HistoryManagerSingleton = new Class({
		
		initialize: function() {
			this._currentLocation = this._getHash();
			
			if (window.ie) {
				this.addState = this._addStateIE;
				this._iframe = new Element('iframe', {
					src: "javascript:'<html></html>'",
					styles: {
						'position': 'absolute',
						'top': '-1000px'
					}
				}).inject(document.body).contentWindow;
				
				$justForIE = function(hash) {
					this._getHash = function() { return hash; }
					this._monitorDefault.call(this);
					location.hash = hash;
				}.bind(this);
				
				var waitForLoad = function waitForIframeLoad() {
					if (this._iframe && this._iframe.document && this._iframe.document.body) {
						if (!this._iframe.document.body.innerHTML)
							this.addState(this._currentLocation, true);
						$clear(waitForLoad);
					}
				}.periodical(250, this);
			}
			else if (window.webkit419) {
				this._form = new Element("form", {method: 'get'}).inject(document.body);
				this._historyCounter = history.length;
				this._stateHistory = [];
				this._stateHistory[history.length] = this._getHash();
				
				this.addState = this._addStateSafari;
				this._monitorSafari.periodical(500, this);
			}
			else if (window.opera && navigator.appVersion.toFloat() < 9.5) {
				this.addState = this._addStateDefault;
	
				$justForOpera =  this._monitorDefault.bind(this);
				new Element('img', {
					src: "javascript:location.href='javascript:$justForOpera();';",
					style: "position: absolute; top: -1000px;"
				}).inject(document.body);
			}
			else {
				this.addState = this._addStateDefault;
				this._monitorDefault.periodical(500, this);
			}
		},
		
		getCurrentLocation: function() {
			return this._currentLocation;
		},
		
		_getHash: function() {
			return location.href.split('#')[1] || '';
		},
		
		_addStateIE: function(hash, override) {
			if (this._currentLocation == hash && !override) return;

			this._currentLocation = hash;
			this._iframe.document.write('<html><body onload="top.$justForIE(\'', hash ,'\');">Loaded</body></html>');
			this._iframe.document.close();
		},
		
		_addStateSafari: function(hash) {
			if (this._currentLocation == hash) return;
	
			this._form.setProperty('action', '#' + hash).submit()
			this._currentLocation = hash;
			this._stateHistory[history.length] = this._getHash();
			this._historyCounter = history.length;
		},
	
		_monitorSafari: function() {
			if (history.length != this._historyCounter) {
				this._historyCounter = history.length;
				this._currentLocation = this._stateHistory[history.length];
				this.fireEvent('onHistoryChange', [this._currentLocation]);
			}
		},
	
		_addStateDefault: function(hash) {
			if (this._currentLocation == hash) return;
			location.hash = '#' + hash;
			this._currentLocation = hash;
		},
	
		_monitorDefault: function() {
			var hash = this._getHash();
	
			if (hash != this._currentLocation) {
				this._currentLocation = hash;
				this.fireEvent('onHistoryChange', [hash]);
			}
		}
	});
	
	HistoryManagerSingleton.implement(new Events);
	
	var singleton;

	return function() {
		return singleton ? singleton : singleton = new HistoryManagerSingleton();
	}
	
})();